Divorce lawyers say January is invariably their busiest month, the post-festive period being the time when unhappy couples tend to reach snapping point. For a manager and a club so patently unsuited as Sam Allardyce and Newcastle United, a run of five games without a win indicated separation could be imminent and it was no real surprise to learn the pair had parted company last night.

Recent suggestions from within the club never rang true that Mike Ashley, the club's billionaire owner, and the chairman, Chris Mort, a corporate lawyer, were determined to think long term and offer Allardyce the time he needed. Quite apart from the fact that Allardyce was not their appointment - the manager having been hired by Freddy Shepherd, Newcastle's former chairman, just days before Ashley's takeover - ruthlessness is a quality billionaires and partners in leading London law firms rarely lack.

Allardyce did not have the sort of broad vision and thick skin required to manage a club as large as Newcastle. Indeed, his mentality could be described as "small-town", something manifested by his cautious, stifling, tactics and prickliness in the face of criticism.

Whereas at Bolton he had controlled every aspect of the club, at Newcastle he struggled to impose his will on a squad, board, crowd and local media often out of sync with his own philosophies. Tyneside may be less than three hours drive from Lancashire but Allardyce found the culture shock immense.

His cause was hardly helped by Ashley's somewhat eccentric decision to "totally immerse" himself in the culture of his new club. This involved a man previously known as a recluse drinking with fans in the Bigg Market, wearing a replica shirt alongside the Toon Army in away ends at places like Wigan, and even travelling to games on supporters' buses.

Such journeys will have fully acquainted Newcastle's owner with the word on the street, and Ashley must have learnt that Allardyce's brutally pragmatic vision of the way the game needed to be played did not exactly excite season-ticket holders.

Long balls crashed towards the corner flags as part of a long throw-propelled percentage game may have worked for a while at Bolton but the stakes are higher and the fans more demanding at Newcastle.

Moreover there were increasing murmurings of dissent from within a dressing room in which Michael Owen was understood to be unhappy at receiving too many balls at throat height, and several other players including Emre Belozoglu and James Milner felt Allardyce's strict game-plans were cramping their creativity.

His squad grew bored during interminable team meetings about how "to stop" opponents, and one brave player once asked: "But what do you want us to do when we're on the ball?"

Such caution is all very well if points are being racked up but Allardyce's spoiling tactics were not very successful and the back four - often manned by at least three of his summer signings - looked as suspect as ever. If the unlamented Titus Bramble was erratic, David Rozehnal and Claudio Cacapa have taken unreliability to new heights, whereas José Enrique looks even worse.

Sir Bobby Robson became so concerned about the lack of style at the team he once managed that he urged Allardyce publicly to "pass it shorter and play carpet football". As obdurate as he could be arrogant, Allardyce responded by using his regular column in Zoo magazine to opine that people "were talking rubbish" about Newcastle's perceived lack of style.

If Mort and co may have been a little puzzled that their manager chose to earn extra cash from a lads' mag while boycotting the BBC in the wake of his disagreement with Panorama, the board were probably more concerned about Allardyce's burgeoning backroom staff. Experts were recruited in every conceivable, and often avant garde, area of sports science but some players privately queried the advice - not to mention numerous supplements - they were being given. Having eaten bread and pasta during years spent terrorising full-backs Damien Duff, the Ireland winger, was told to omit such carbohydrates from his diet.

Reportedly 32-strong, Allardyce's support staff was certainly large enough for the manager to have spared "two of the fitness lads" he sent to Hampshire in order to keep Joey Barton in shape while he receives therapy for behavioural problems in the Sporting Chance Clinic.

Barton's signature for £5.8m from Manchester City last summer represented another nail in his manager's coffin. The troubled midfielder arrived with "history" and only after Allardyce had worked hard to persuade Mort and Ashley that he really would be the man to tame him. Instead Barton was arrested in Liverpool in late December, charged with assault, initially remanded and then bailed on the condition he remains in Sporting Chance's care until his next hearing, on Wednesday.

Only yesterday Allardyce talked of his plans to visit the errant midfielder but now Barton is someone else's problem, and Big Sam is just another name on the long list of former Newcastle managers.